Solid-state imaging apparatus

ABSTRACT

A solid-state imaging apparatus includes: a solid-state imaging device photoelectrically converting light taken by a lens; and a light shielding member shielding part of light incident on the solid-state imaging device from the lens, wherein an angle made between an edge surface of the light shielding member and an optical axis direction of the lens is larger than an incident angle of light to be incident on an edge portion of the light shielding member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/114,642, filed Aug. 28, 2018, which is a continuation of U.S. patentapplication Ser. No. 15/961,250, filed Apr. 24, 2018, which is acontinuation of U.S. patent application Ser. No. 15/836,173, filed Dec.8, 2017, now U.S. Pat. No. 9,978,794, which is a continuation of U.S.patent application Ser. No. 15/495,679, filed Apr. 24, 2017, now U.S.Pat. No. 9,911,776, which is a continuation of U.S. patent applicationSer. No. 15/443,853, filed Feb. 27, 2017, now U.S. Pat. No. 9,799,692,which is a continuation of U.S. patent application Ser. No. 15/443,568,filed Feb. 27, 2017, now U.S. Pat. No. 9,842,872, which is acontinuation of U.S. patent application Ser. No. 15/430,107, filed Feb.10, 2017, now U.S. Pat. No. 9,871,069, which is a continuation of U.S.patent application Ser. No. 15/379,181, filed Dec. 14, 2016, now U.S.Pat. No. 9,773,826, which is a continuation of U.S. patent applicationSer. No. 15/192,474 filed Jun. 24, 2016, now U.S. Pat. No. 9,620,543,which is a continuation of U.S. patent application Ser. No. 14/798,858,filed Jul. 14, 2015, now U.S. Pat. No. 9,391,106, which is acontinuation of U.S. patent application Ser. No. 14/317,781, filed Jun.27, 2014, now U.S. Pat. No. 9,105,541, which is a continuation of U.S.patent application Ser. No. 13/357,883 filed Jan. 25, 2012, now U.S.Pat. No. 8,786,041, the entire contents of each of which is incorporatedherein by reference. U.S. patent application Ser. No. 13/357,883 isbased upon and claims the benefit of priority from Japanese PatentApplication Nos. 2011-033690 and 2011-105241 filed Feb. 18, 2011 and May10, 2011, respectively, the entire contents of each of which isincorporated herein by reference.

FIELD

The present disclosure relates to a solid-state imaging apparatus andparticularly relates to a solid-state imaging apparatus capable ofsuppressing generation of flare and ghost.

BACKGROUND

In recent years, chip shrink tends to make progress due to introductionof a leading-edge process also in an image sensor in the solid-stateimaging apparatus in the same manner as other semiconductor chips.Accordingly, it is possible to consider to design the image sensor sothat bonding pads are arranged within a lens effective diameter whendesigning the solid-state imaging apparatus in which the image sensor isconnected to a substrate by wire bonding.

However, in such case, there is a danger of generating flare or ghost aslight incident from the lens is reflected on surfaces of wires (metalwires) connected to the bonding pads and enters a light receivingsurface on the image sensor.

In respond to this, there is disclosed a solid-state imaging apparatuswhich includes a light shielding member for shielding light in lightfrom the lens incident on the periphery of the bonding pads arranged onthe image sensor (for example, JP-A-2006-222249 (Patent Document 1)).

According to the above, it is possible to suppress flare and ghostcaused by light incident from the lens being reflected on the surfacesof the metal wires connected to the bonding pads and entering the lightreceiving surface on the image sensor.

SUMMARY

In manufacturing processes of the solid-state imaging apparatus, aposition of the light shielding member in the image sensor has givenvariation with respect to the position on design.

For example, as shown on the left of FIG. 1, when a distance between anend portion of a light receiving surface 1 a of an image sensor 1 and anedge portion of an opening of a light shielding member 3 bonded to asurface of an IRCF (Infrared Ray Cut Filter) 4 facing the image sensor 1is “d1”, incident light represented by a bold arrow is shielded by thelight shielding member 3 and does not reach a metal wire 2. Even whenthe incident light is reflected on an edge surface of the opening of thelight shielding member 3, the reflected light does not reach the lightreceiving surface 1 a of the image sensor 1. Assume that the incidentlight represented by the bold arrow in the drawing is light whoseincident angle on the image sensor 1 is the largest of incident lightfrom a not-shown lens. Also, assume that the edge surface of the openingof the light shielding member 3 is parallel to an optical axis direction(direction from top to bottom in the drawing) of the lens.

On the other hand, as shown on the right of FIG. 1, the distance betweenthe end portion of the light receiving surface 1 a of the image sensor 1and the edge portion of the opening of the light receiving member 3 is“d2”, incident light represented by a bold arrow is shielded by thelight shielding member 3 and does not reach the metal wire 2. However,when the incident light is reflected on the edge surface of the openingof the light shielding member 3, the reflected light enters the lightreceiving surface 1 a on the image sensor 1.

In this case, flare or ghost caused by reflected light from the surfaceof the metal wire 2 connected to the bonding pad can be suppressed,however, flare or ghost is caused due to reflected light from the edgesurface of the opening of the light shielding member 3.

In view of the above, it is desirable to suppress generation of flareand ghost.

An embodiment of the present disclosure is directed to a solid-stateimaging apparatus including a solid-state imaging devicephotoelectrically converting light taken by a lens, and a lightshielding member shielding part of light incident on the solid-stateimaging device from the lens, in which an angle made between an edgesurface of the light shielding member and an optical axis direction ofthe lens is larger than an incident angle of light to be incident on theedge surface of the light shielding member.

The angle made between the edge surface of the light shielding memberand the optical axis direction of the lens may be larger than theincident angle of light whose incident angle is the largest of lightincident on an edge portion of the light shielding member.

Pads to which metal wires connected to a substrate are connected may beprovided at an peripheral portion of a light receiving surface of thesolid-state imaging device, and it is possible that the pads are notarranged on an area closer to the light receiving surface in areasdefined by an intersection between a surface of the solid-state imagingdevice and a virtual extension surface of the edge surface of the lightshielding member.

The light receiving surface of the solid-state imaging device receiveslight incident from an opening of the substrate having the opening, andit is possible that an edge surface of the opening does not intersectthe virtual extension surface of the edge surface of the light shieldingmember.

The solid-state imaging apparatus may further include a sealing membersealing a gap on the light receiving surface of the solid-state imagingdevice, in which the light shielding member may be provided on a surfaceof the sealing member facing the lens or a surface thereof facing thesolid-state imaging device.

A side surface of the sealing member may be configured not to intersectthe virtual extension surface of the edge surface of the light shieldingmember.

The shielding member may be formed by printing a material for printingon an optical filter arranged on an optical path once or plural times.

According to the embodiment of the present disclosure, the angle madebetween the edge surface of the light shielding member and the opticalaxis direction of the lens is allowed to be larger than the incidentangle of light to be incident on the edge portion of the light shieldingmember.

According to the embodiment of the present disclosure, generation offlare and ghost can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is views for explaining reflection on an edge surface of anopening of a related-art light shielding member;

FIG. 2 is a view showing an example of an exterior structure of asolid-state imaging device to which the present disclosure is applied;

FIG. 3 is a view for explaining a position of a light shielding memberand an angle made at an edge surface thereof;

FIG. 4 is a view for explaining the position of the light shieldingmember and the angle made at the edge surface thereof;

FIG. 5 is a view for explaining the position of the light shieldingmember and the angle made at the edge surface thereof;

FIG. 6 is a flowchart for explaining processing of forming the lightshielding member;

FIG. 7 is a view for explaining printing of a material for printing asthe light shielding member;

FIG. 8 is a view for explaining reflection on an edge surface of anopening of a substrate of a flip-chip structure;

FIG. 9 is a view showing a structure example of a solid-state imagingapparatus of the flip-chip structure to which the present disclosure isapplied;

FIG. 10 is a view showing another structure example of the solid-stateimaging apparatus of the flip-chip structure;

FIG. 11 is a view showing a structure example of a solid-state imagingapparatus in which cavity-less is realized;

FIG. 12 is a view showing a structure example of the solid-state imagingapparatus in which cavity-less is realized;

FIG. 13 is a view showing a structure example of the solid-state imagingapparatus in which cavity-less is realized;

FIG. 14 is a view showing a structure example of the solid-state imagingapparatus in which cavity-less is realized;

FIG. 15 is a cross-sectional view of a solid-state imaging apparatus inwhich a periphery of an edge portion of the opening of the lightshielding member is folded;

FIG. 16 is a view for explaining conditions of reflection of incidentlight at an upper surface of a folded portion of the light shieldingmember;

FIG. 17 is a view for explaining conditions of transmission of incidentlight at the edge surface of the opening of the light shielding member;

FIGS. 18A to 18C shows graphs for explaining values of an cut angle tobe made at the edge surface of the opening of the light shieldingmember;

FIG. 19 is a flowchart for explaining processing of forming the lightshielding member by metal molds;

FIGS. 20A and 20B are views for explaining formation of the lightshielding member by metal molds;

FIG. 21 is a view for explaining formation of the light shielding memberby metal molds;

FIGS. 22A and 22B are views for explaining formation of the lightshielding member by metal molds;

FIGS. 23A to 23C are views for explaining formation of the lightshielding member by metal molds; and

FIGS. 24A and 24B are views for explaining formation of the lightshielding member by metal molds.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the present disclosure will be explainedwith reference to the drawings. The explanation will be made in thefollowing order.

1. Solid-state imaging apparatus of a wire bonding structure

2. Solid-state imaging apparatus of a flip-chip structure

3. Example of a solid-state imaging apparatus in which cavity-less isrealized

4. Example of forming a light shielding member by metal molds

<1. Solid-State Imaging Apparatus of a Wire Bonding Structure>

[Exterior Structure of a Solid-State Imaging Apparatus]

FIG. 2 is a view showing a structure of a solid-state imaging deviceaccording to an embodiment to which the present disclosure is applied.

A solid-state imaging apparatus of FIG. 2 includes a CMOS image sensor10 (hereinafter referred to merely as the image sensor 10) as an opticalsensor, metal wires 11 connecting the image sensor 10 to a not-shownsubstrate electrically, a passive component 12 mounted on the not-shownsubstrate and a light shielding member 13 shielding part of lightincident on the image sensor 10 from a not-shown lens.

The image sensor 10 has a light receiving surface 10 a in which unitpixels (hereinafter referred to merely as pixels) having photoelectricconversion devices are two-dimensionally arranged in a matrix state,detecting a charge amount corresponding to the amount of light incidenton the light receiving surface 10 a as a physical value on a pixelbasis.

Bonding pads which are terminals for connecting metal wires 11 arearranged on a peripheral portion of the image sensor 10 excluding thelight receiving surface 10 a, and the metal wires 11 connected to thebonding pads are connected to a not-shown substrate by wire bonding.

In the image sensor 10, at least part of the bonding pads is arranged inan effective diameter of a not-shown lens.

The light shielding member 13 is made of a film having a given thicknessand colored black, having an opening through which incident light to beincident on the light receiving surface 10 a of the image sensor 10 fromthe not-shown lens. The light shielding member 13 is arranged on anoptical path between the lens and the image sensor 10, which is bondedto, for example, a surface of an IRCF (Infrared Ray Cut Filter) 31facing the image sensor 10, which is an optical filter including aninfrared ray absorbing material as shown in FIG. 3 to FIG. 5. This isbecause there is a danger that incident light from the lens is reflectedon a lower surface (surface facing the image sensor 10) of the IRCF 31to be stray light and causes flare and ghost when the light shieldingmember 13 is bonded to a surface of the IRCF 31 facing the lens (upperside in the drawing).

Most of the incident light from the lens is incident on the lightreceiving surface 10 a of the image sensor 10 from the opening of thelight shielding member 13, however, incident light to be incident on thevicinity of the bonding pads arranged on the peripheral portion of theimage sensor 10 in incident light from the lens is shielded by the lightshielding member 13.

Accordingly, it is possible to suppress flare and ghost caused byincident light from the lens being reflected on surfaces of the metalwires 11 in the vicinity of the bonding pads and entering the lightreceiving surface 10 a on the image sensor 10.

Furthermore, a given angle is made with respect to the optical axisdirection of the lens at the edge surface of the opening of the lightshielding member 13, and incident light to be incident on the edgeportion of the opening of the light shielding member 13 can betransmitted without being reflected on the edge surface. The angle to bemade at the edge surface of the opening of the light shielding member 13can be obtained by molding the film as the light shielding member 13 bymetal molds.

[Positions of the Light Shielding Member and the Angle made at the EdgeSurface]

Here, positions of the light shielding member 13 with respect to theimage sensor 10 and the angle to be made at the edge surface of theopening of the light shielding member 13 will be explained withreference to FIG. 3 to FIG. 5. Hereinafter, the edge surface of theopening of the light shielding member 13 is appropriately referred tomerely as the edge surface of the light shielding member 13.

The position of the light shielding member 13 with respect to the imagesensor 10 varies to some degree, however, the image sensor 10 ismanufactured so that the variation will be within a certain range.Curves shown in FIG. 3 to FIG. 5 are distribution curves indicatingvariation in position of the edge portion (edge surface) of the lightshielding member 13. That is, the position of the light shielding member13 shown in FIG. 4 indicates a position in design and positions of thelight shielding member 13 shown in FIG. 3 and FIG. 5 indicate positionsshifted from the position in design by the maximum error σ.

When a chief ray from the lens is incident on the light receivingsurface 10 a of the image sensor 10 at a certain incident angle (CRA:Chief Ray Angle), an upper ray and a lower ray corresponding to thechief ray are incident at respective incident angles.

In FIG. 3, the upper ray corresponding to the chief ray incident on theend portion of the light receiving surface 10 a is not shielded by thelight shielding member 13, and the chief ray, the upper ray and thelower ray corresponding to the chief ray will be incident on the lightreceiving surface 10 a without exception.

In FIG. 5, the lower ray transmitted without being shielded by the lightshielding member 13 is set so as not to be reflected on the metal wires11.

That is, the position of the light shielding member 13 with respect tothe image sensor 10 will be a position where the chief ray, the upperray and the lower ray corresponding to the chief ray will be incident onthe light receiving surface 10 a without exception in the edge portionof the opening of the light shielding member 13 as well as the lower rayis not incident on the bonding pads (metal wires 11).

When the edge surface of the light shielding member 13 is angled withrespect to the optical axis direction of the lens so that the lower raywhose incident angle is the largest of the chief ray, the upper ray andthe lower ray transmits through the edge portion of the opening of thelight shielding member 13, incident light is not reflected on the edgesurface of the light shielding member 13. That is, an angle made betweenthe edge surface of the light shielding member 13 and the optical axisdirection of the lens (hereinafter referred to as an edge surface angle)may be an angle larger than the incident angle of the lower ray to beincident on the edge portion of the opening of the light shieldingmember 13.

That is, when the edge surface angle is θM: and the incident angle ofthe lower ray is θL, it is preferable to satisfy θM>θL as shown in FIG.5. The incident angle θL of the lower ray is represented as thefollowing expression (1) when an incident angle θU of the upper ray, adistance D between the edge portion of the light receiving surface 10 aand the bonding pad and a distance (gap length) G between the IRCF 31and the surface of the image sensor 10 are used.θL=arctan[tan θU+{(D−2σ)/G}]  (1)

Accordingly, the edge surface angle θM will be given so as to satisfythe following expression (2).θM>arctan[tan θU+{(D−2σ)/G}]  (2)

Specifically, for example, when the CRA of the chief ray is 30 degrees,incident angles of the upper ray and the lower ray corresponding to thechief ray are ±10 degrees of the CRA, therefore, the lower ray is notreflected on the edge surface of the light shielding member 13 bydetermining the edge surface angle to be 50 degrees including a margin.

Furthermore, the lower ray transmitted through the edge portion of theopening of the light shielding member 13 is not incident on surfaces ofthe metal wires 11 connected to the bonding pads as described above. Inother words, the bonding pads for connecting the metal wires 11 aredesigned not to be arranged on an area closer to the light receivingsurface 10 a in areas defined by an intersection between the surface ofthe image sensor 10 and a virtual extension surface of the edge surfaceof the light shielding member 13.

According to the above structure, incident light is not reflected on theedge surface of the light shielding member 13, therefore, it is possibleto suppress the generation of flare and ghost due to reflected lightfrom the edge surface of the light shielding member 13.

Additionally, the lower ray transmitted through the edge portion of theopening of the light shielding member 13 is not reflected on surfaces ofthe metal wires 11 connected to the bonding pads, therefore, it is alsopossible to suppress the generation of flare and ghost due to reflectedlight from the surfaces of the metal wires 11.

Particularly, as the CRA of the chief ray is increased, the incidentangle of the lower ray is also increased in a back-illuminated imagesensor. The edge surface of the light shielding member 13 is formed soas to correspond to the incident angle of the lower ray, therebysuppressing generation of flare and ghost.

As the generation of flare and ghost can be suppressed even when atleast part of the bonding pads is arranged in the effective diameter ofthe lens in the image sensor 10, therefore, the chip size of the imagesensor 10 can be reduced. Accordingly, the theoretical yield can beincreased and costs per one chip can be reduced.

Moreover, the bonding pads can be arranged in the vicinity of the lightreceiving surface 10 a in the image sensor 10, therefore, the scale ofperipheral circuits of the image sensor 10 can be also made small, whichallows the process generation in the semiconductor chip to makeprogress. As a result, an image sensor responding to the reduction ofpower consumption and improvement in operation speed can be provided.

Furthermore, as the chip size of the image sensor 10 can be reduced, thesize of a camera module including the image sensor 10 can be alsoreduced, therefore, the technique can be applied to a cellular phonewith a camera in which miniaturization is particularly demanded.

[Materials for the Light Shielding Member]

Though the light shielding member 13 is made of the black-colored filmin the above description, the light shielding member 13 can be made ofother materials.

Specifically, for example, the light shielding member 13 can be made byprinting materials for printing on the IRCF 31. The materials forprinting are, for example, a carbon filler, epoxy resin or acrylic resincolored black with dye, an epoxy/acrylic hybrid resin and so on, whichhave UV curability or heat curability. The materials for printing can beresins having normal-temperature curability. As a printing method of theabove materials for printing, a screen printing method, an ink-jetprinting method or the like is applied.

[Processing of Forming the Light Shielding Member by Printing]

Here, the processing of forming the light shielding member 13 byprinting will be explained with reference to a flowchart of FIG. 6.

In Step S11, the material for printing is printed on the IRCF 31. InStep S12, whether a film thickness is sufficient or not is determined.When it is determined that the film thickness is not sufficient in StepS12, the printed material for printing is cured, then, the processreturns to Step S11 and the material for printing is printed again.

On the other hand, when it is determined that the film thickness issufficient, the printed material for printing is cured, then, theprocess ends.

In the case where the material for printing has the UV curability, thefilm thickness will be approximately 10 μm by one printing, therefore,the light shielding member 13 having a film thickness of approximately50 μm can be obtained by printing of three or four times.

When the light shielding member 13 is printed by a liquid material forprinting, the edge surface angle of the light shielding member 13 isobtained as a contact angle of the material for printing to beprescribed by wettability of the IRCF 31, and a cross section thereofwill be as shown in FIG. 7. The edge surface angle can be obtained by amanner of stacking the material for printing in printing of pluraltimes.

Furthermore, the light shielding material 13 can be formed by, forexample, depositing a thin film on the IRCF 31. In this case, etching isperformed so that side etching is accomplished at the time of patterningthe opening with respect to the deposited thin film.

The solid-state imaging apparatus in which the image sensor is connected(mounted) on the substrate by wire bonding has been explained as theabove, and a solid-state imaging apparatus having a flip-chip structurewill be explained below.

<2. Solid-State Imaging Apparatus of a Flip-Chip Structure>

[Related-Art Solid-State Imaging Apparatus of the Flip-Chip Structure]

FIG. 8 is a view showing a structure of a related-art solid-stateimaging apparatus of the flip-chip structure.

In a solid-state imaging apparatus shown in FIG. 8, a CMOS image sensor110 (hereinafter referred to merely as the image sensor 110) iselectrically connected to a substrate 111 having an opening throughbumps 112. Connecting portions between the image sensor 110 and thesubstrate 111 by the bumps 112 are sealed by an under fill (UF) 113 madeof an epoxy resin and so on. On the opening of the substrate 111, a sealglass 114 as a seal member for protecting an upper portion of a lightreceiving surface 110 a of the image sensor 110 is bonded by aUV-curable adhesive member 115 (FIG. 9). The UV-curable adhesive member115 can be a heat curable member. The seal glass 114 is made of atransparent material transmitting light, and incident light from anot-shown lens represented by bold arrows in the drawing is incident onthe light receiving surface 110 a of the image sensor 110 through theseal glass 114. The seal glass 114 can be the IRCF. In the solid-stateimaging apparatus having the flip-chip structure shown in FIG. 8, a gapis formed between the surface of the seal glass 114 which faces thelight receiving surface 110 a and the light receiving surface 110 a.

In the flip-chip structure, the light receiving surface 110 a, theopening of the substrate 111 and an edge surface of the UF 113 arepositioned relatively close to one another. Therefore, reflected lightreflected on the opening of the substrate 111 or the edge surface of theUF 113 in incident light to be incident through the seal glass 114enters the light receiving surface 110 a, which may cause the generationof flare and ghost.

Accordingly, as shown in FIG. 9, light to be incident on the opening ofthe substrate 111 and the edge surface of the UF 113 in light from thenot-shown lens is shielded by a light shielding member 131 by adheringthe light shielding member 131 to the seal glass 114 as shown in FIG. 9.

[Application of the Light Shielding Member to the Flip-Chip Structure]

FIG. 9 is a view showing a structure of a solid-state imaging apparatushaving the flip-chip structure according to the embodiment to which thepresent disclosure is applied. FIG. 9 shows only a structure of aportion corresponding to a portion surrounded by a dotted square framein the solid-state imaging apparatus of FIG. 8. In the solid-stateimaging apparatus of FIG. 9, components corresponding to components ofthe solid-state imaging apparatus of FIG. 8 are denoted by the samesymbols.

In FIG. 9, the light shielding member 131 is made of a film having agiven thickness and colored black, having an opening through which lightto be incident on the light receiving surface 110 a of the image sensor110 from the not-shown lens in the same manner as the light shieldingmember 13 of FIG. 2. The light shielding member 131 is bonded to asurface of the seal glass 114 facing the image sensor 110. The lightshielding member 131 is made of the black colored film in the abovedescription, however, the light shielding member 131 can be made ofmaterials for printing to be printed on the seal glass 144 as well asmade of the thin film to be deposited on the seal glass in the samemanner as the light shielding member 13 described above.

In the case where the chief ray is incident on the light receivingsurface 110 a of the image sensor 110 with a certain CRA, the upper rayand the lower ray corresponding to the chief ray are also incident atrespective incident angles.

When the edge surface of the light shielding member 131 is angled withrespect to the optical axis direction of the lens so that the lower raywhose incident angle is the largest of the chief ray, the upper ray andthe lower ray transmits through the edge portion of the opening of thelight shielding member 131, incident light is not reflected on the edgesurface of the light shielding member 131. That is, the edge surfaceangle of the light shielding member 131 will be larger than the incidentangle of the lower ray to be incident on the edge portion of the openingof the light shielding member 131.

Additionally, a width L of the light shielding member 131 is designed sothat edge surfaces of the opening of the substrate 111 and the UF 113 donot intersect the virtual extension surface of the edge surface of thelight shielding member 131. That is, the lower ray transmitted throughthe edge portion of the opening of the light shielding member 131 is notreflected on the edge surfaces of the opening of the substrate 111 andthe UF 113.

According to the above structure, incident light is not reflected on theedge surface of the light shielding member 131 as well as incident lightis not reflected on the edge surfaces of the opening of the substrate111 and the UF 113, therefore, it is possible to suppress the generationof flare and ghost due to reflected light from the edge surface of thelight shielding member 131, the edge surface of the opening of thesubstrate 111 or the edge surface of the UF 113.

Though the seal glass 114 and the opening of the substrate 111 arebonded together by the adhesive member 115 in FIG. 9, it is alsopreferable that the light shielding member 131 bonds the seal glass 114and the opening of the substrate 111 by using a material having anadhesive function as the light shielding member 131.

Though the light shielding member 131 is bonded to the surface of theseal glass 114 facing the image sensor 110 in the above example,however, it is also preferable that the light shielding member 131 isbonded to the surface opposite to the surface (surface facing the lens)of the seal glass 114 facing the image sensor 110 as shown in FIG. 10.

The light receiving surface of the image sensor is exposed in the gap(hereinafter referred to as a cavity) in the above structure of thesolid-state imaging apparatus, therefore, the image sensor tends to beaffected by dust. In response to this, a solid-state imaging apparatusin a structure not having the cavity (hereinafter referred to as acavity-less structure) is proposed for reducing effects of dust in thelight receiving surface of the image sensor.

Here, an example of the solid-state imaging apparatus of the cavity-lessstructure to which the present disclosure is applied will be explained.

<3. Example of a Solid-State Imaging Apparatus of a Cavity-LessStructure>

[Cavity-Less Solid-State Imaging Apparatus of the Wire BondingStructure]

FIG. 11 is a view showing a structure of a solid-state imaging apparatusof the wire bonding structure in which cavity-less is realized. In thesolid-state imaging apparatus of FIG. 11, components corresponding tocomponents of the solid-state imaging apparatuses of FIG. 3 and so onare denoted by the same symbols.

That is, the solid-state imaging apparatus of FIG. 11 has a structure inwhich a glass layer 211, a light shielding member 212 and a resin layer213 are newly provided while removing the light shielding member 13 inthe solid-state imaging apparatuses of FIG. 3 and so on.

The glass layer 211 and the resin layer 213 are made of transparentmaterials transmitting light, refractive indexes of which are higherthan air. In the solid-state imaging apparatus of FIG. 11, the cavity issealed by the glass layer 211 and the resin layer 213 to thereby realizethe cavity-less structure.

Moreover, the light shielding member 212 is bonded to a lower surface ofthe glass layer 211 (surface facing the image sensor 10). The lightshielding member 212 is formed by the same material and shape as theabove light shielding member 13.

The width (a length in the transverse direction in the drawing) of thelight shielding member 212 is designed so that a side surface of theresin layer 213 does not intersect a virtual extension surface of anedge surface of the light shielding member 212. That is, the lower raytransmitted through the edge portion of the opening of the lightshielding member 212 is not reflected on the side surface of the resinlayer 213.

In manufacturing processes, after the light shielding member 212 isbonded to the lower surface of the glass layer 211, the positioning ofthe light shielding member 212 is performed with respect to the imagesensor 10 in the wafer level, then, the glass layer 211 is bonded to theimage sensor 10 with the resin layer 213. Next, dicing is performed toobtain a single piece, then, the glass layer 211 and the resin layer 213are cut for exposing a bonding pad portion. After that, the exposedbonding pad portion is cleaned to thereby form bonding pads asterminals. It is also preferable that the glass layer 211 is bonded tothe image sensor 10 with the resin layer 213 after the image sensor 10is formed as a chip. In this case, the process of cleaning the exposedbonding pad portion can be omitted.

Also in the solid-state imaging apparatus of the wire bonding structurein which cavity-less is realized in the manner as described above,incident light is not reflected on the edge surface of the lightshielding member 212, therefore, it is possible to suppress thegeneration of flare and ghost due to reflected light from the edgesurface of the light shielding member 212.

Moreover, the lower ray transmitted through the edge surface portion ofthe light shielding member 212 is not reflected on the side surface ofthe resin layer 213, therefore, it is also possible to suppress thegeneration of flare and ghost due to reflected light from the sidesurface of the resin layer 213.

The structure in which the light shielding member 212 is bonded to thelower surface of the glass layer 211 has been explained as the above,and it is also preferable to apply a structure in which the lightshielding member 212 is bonded to an upper surface of the glass layer211 as shown in FIG. 12. In this case, the light shielding member 212can be bonded to the upper surface of the glass layer 211 after theglass layer 211, the resin layer 213 and the image sensor 10 are bondedtogether, therefore, the accuracy of positioning the light shieldingmember 212 with respect to the image sensor 10 can be increased. As itis difficult to angle the edge surface of the light shielding member 212using the wettability with respect to the glass layer 211 in FIG. 12,the light shielding member 212 made of a black-colored film will beapplied.

Also in the solid-state imaging apparatus of FIG. 12, the width of thelight shielding member 212 (a length in the transverse direction in thedrawing) is designed so that the side surfaces of the glass layer 211and the resin layer 213 do not intersect the virtual extension surfaceof the edge surface of the light shielding member 212. That is, thelower ray transmitted through the edge portion of the opening of thelight shielding member 212 is not reflected on the side surfaces of theglass layer 211 and the resin layer 213.

[Cavity-Less Solid-State Imaging Apparatus of the Flip-Chip Structure]

FIG. 13 is a view showing a structure of a solid-state imaging apparatusof the flip-chip structure in which cavity-less is realized. In thesolid-state imaging apparatus of FIG. 13, components corresponding tocomponents of the solid-state imaging apparatus of FIG. 8 or FIG. 9 aredenoted by the same symbols.

That is, the solid-state imaging apparatus of FIG. 13 has a structure inwhich a glass layer 311, a light shielding member 312 and a resin layer313 are newly provided while removing the seal glass 114 and the lightshielding member 131 in the solid-state imaging apparatus of FIG. 8 ofFIG. 9.

The glass layer 311 and the resin layer 313 are made of transparentmaterials transmitting light, refractive indexes of which are higherthan air. In the solid-state imaging apparatus of FIG. 13, the cavity issealed by the glass layer 311 and the resin layer 313 to thereby realizethe cavity-less structure.

Moreover, the light shielding member 312 is bonded to a lower surface ofthe glass layer 311 (surface facing the image sensor 110). The lightshielding member 312 is formed by the same material and shape as theabove light shielding member 131.

The width (a length in the transverse direction in the drawing) of thelight shielding member 312 is designed so that a side surface of theresin layer 313 does not intersect a virtual extension surface of anedge surface of the light shielding member 312. That is, the lower raytransmitted through the edge portion of the opening of the lightshielding member 312 is not reflected on the side surface of the resinlayer 313.

In manufacturing processes, after the light shielding member 312 isbonded to the lower surface of the glass layer 311, the positioning ofthe light shielding member 312 is performed with respect to the imagesensor 110 in the wafer level, then, the glass layer 311 is bonded tothe image sensor 110 with the resin layer 313. Then, TSV (ThroughSilicon Via) process for piercing through the chip from the front to theback is performed in the image sensor 110 to thereby realize CSP (ChipScale Package).

Also in the solid-state imaging apparatus of the flip-chip structure inwhich cavity-less is realized, incident light is not reflected on theedge surface of the light shielding member 312 or the edge surfaces ofthe opening of the substrate 111 and the UF 113, therefore, it ispossible to suppress the generation of flare and ghost due to reflectedlight from the the edge surface of the light shielding member 312 or theedge surfaces of the opening of the substrate 111 and the UF 113.

The structure in which the light shielding member 312 is bonded to thelower surface of the glass layer 311 has been explained as the above,and it is also preferable to apply a structure in which the lightshielding member 312 is bonded to an upper surface of the glass layer311 as shown in FIG. 14. In this case, the light shielding member 312can be bonded to the upper surface of the glass layer 311 after theglass layer 311, the resin layer 313 and the image sensor 110 are bondedtogether, therefore, the accuracy of positioning the light shieldingmember 312 with respect to the image sensor 110 can be increased. As itis difficult to angle the edge surface of the light shielding member 312using the wettability with respect to the glass layer 311 in FIG. 14,the light shielding member 312 made of a black-colored film will beapplied.

Also in the solid-state imaging apparatus of FIG. 14, the width of thelight shielding member 312 (a length in the transverse direction in thedrawing) is designed so that the side surfaces of the glass layer 311and the resin layer 313 do not intersect a virtual extension surface ofthe edge surface of the light shielding member 312. That is, the lowerray transmitted through the edge portion of the opening of the lightshielding member 312 is not reflected on the side surfaces of the glasslayer 311 and the resin layer 313.

In the above description, the light shielding member includes theopening through which light incident on the light receiving surface ofthe image sensor from the lens is transmitted, however, the lightshielding member may have structures/shapes corresponding to thearrangement of metal wires in the wire bonding structure or the shape ofthe opening of the substrate in the flip chip structure. For example, inthe case where the bonding pads to which metal wires 11 are connected inthe image sensor 10 of FIG. 2 are arranged only on the right side, thelight shielding member 13 may have the shape to shield the vicinity ofthe bonding pads.

Incidentally, in recent camera modules, the effective diameter of thelens is becoming larger as compared with the size of the image sensorfor the purpose of shortening a focal length or improving a condensingrate of the lens along with the miniaturization of the camera modules.In such case, the incident angle of incident light from the lens becomesfurther larger, therefore, it is necessary to increase the edge surfaceangle of the light shielding member so as to correspond to the incidentangle. For example, when the incident angle of incident light from thelens is 45 degrees, it is necessary to increase the edge surface angleof the light shielding member to be larger than 45 degrees.

The method of printing the material for printing on the IRCF as one ofmethods of forming the light shielding member having the edge surfaceangle has been explained as the above with reference to FIG. 6. However,when the light shielding member is molded by metal molds, for example,it is difficult to form the light shielding member having a large edgesurface angle such as 45 degrees, and the edge surface angle will beapproximately 30 degrees at the maximum.

Accordingly, an example of forming the light shielding member having alarge edge surface angle by metal molds will be explained.

<4. Example of Forming the Light Shielding Member by Metal Molds>

As described above, it is difficult to form the light shielding memberhaving the large edge surface angle by the metal molds, therefore, agiven range from an edge portion of the opening of the light shieldingmember is folded in the direction of the image sensor at a given angle,thereby increasing the edge surface angle.

[Conditions for Suppressing Generation of Flare and Ghost]

FIG. 15 is a cross-sectional view of a solid-state imaging apparatus inwhich a given range from the edge portion of the opening of the lightshielding member is folded in the direction of the image sensor at agiven angle.

In the structure shown in FIG. 15, the following two conditions shouldbe satisfied for suppressing generation of flare and ghost.

(1) A reflected light A′ obtained by an upper ray A from a lens 501being reflected on an upper surface (surface facing the lens) of aportion (hereinafter referred to as a folded portion) of an edge portionof the opening of a light shielding member 502 which is folded in thedirection of an image sensor 503 does not enter the image sensor 503.

(2) A lower ray B from the lens 501 is not reflected on the edge surfaceof the opening of the light shielding member 502 and transmits throughthe opening of the light shielding member 502. The bonding pads forconnecting metal wires 504 are arranged so that the lower ray Btransmitted through the opening of the light shielding member 502 is notincident on the pads.

Here, assume that an effective diameter of the lens 501 is “R”, anopening diameter of the light shielding member 502 is “L”, a distance(focal length) between the lens 501 and the light shielding member 502is “H”, an angle of the folded portion (hereinafter referred to as anfolded angle) with respect to the light shielding member 502 is “γ” andan angle (hereinafter referred to as a cut angle) made at the edgesurface of the light shielding member 502 by the molding processing is“φ” in the following description. Moreover, assume that the incidentangle of the upper ray A is −θU, the incident angle of the lower ray Bis θL and the edge surface angle (namely, an angle made between the edgesurface of the light shielding member 502 and the optical axis directionof the lens 501) is θM. “−θU” as the incident angle of the upper ray Aindicates an angle on the opposite side of the incident angle of theupper ray explained with reference to FIG. 5 with respect to the opticalaxis direction, therefore, a sign of “−” is given.

First, in order to satisfy the condition (1), it is necessary to allowthe angle made between the upper ray A and the reflected light A′ islower than 90°−θU.

That is, as shown in FIG. 16, when a segment OP is given in the verticaldirection on the upper surface of the folded portion of the lightshielding member 502, it is necessary that an angle ∠AOP made betweenthe upper ray A and the segment OP satisfies the following expression(3).∠AOP≤(90°−θU)/2  (3)

When a segment OQ is given in the optical axis direction of the lens 501on the upper surface of the folding portion of the light shieldingmember 502, it is necessary that an angle ∠QOP made between the segmentOQ and the segment OP satisfies the following expression (4).∠QOP≤(90°−θU)/2+θU=(90°+θU)/2  (4)

The angle ∠QOP is equal to the folded angle γ and the incident angle −θUof the upper ray A is represented by arctan {(R−L)/2H}, therefore, thefollowing expression (5) should be satisfied for satisfying thecondition (1).γ≤[90°-arctan {(R−L)/2H}]/2  (5)

Next, θL≤θM should be satisfied for satisfying the above condition (2)as shown in FIG. 17. Here, the incident angle θL of the lower ray B isrepresented by arctan {(R+L)/2H}, therefore, the following expression(6) should be satisfied for satisfying the condition (2).arctan {(R+L)/2H}≤θM  (6)

As described above, the expression (5) and the expression (6) should besatisfied for satisfying the condition (1) and the condition (2).

Incidentally, it is necessary that the edge surface angle θM and thefolded angle γ satisfy the relation of θM>γ, the cut angle φ should bemade at the edge surface of the light shielding member 502 so as tosatisfy θM−γ≤φ.

That is, when the effective diameter R of the lens, the opening diameterL of the light shielding member 502 and the focal length H are fixed bythe above expression (5) and the expression (6), the edge surface angleθM and the folded angle γ satisfying the condition (1) and the condition(2) are fixed, therefore, the minimum value of the cut angle φ to bemade at the edge surface of the light shielding member 502 can be fixed.

FIGS. 18A to 18C are graphs explaining ranges of values of the cut angleφ when the effective diameter R of the lens, the opening diameter L(opening of a light shielding plate) of the light shielding member 502and the focal length H are fixed.

FIG. 18A shows the range of values of the cut angle φ when the focallength H is 8 mm, FIG. 18B shows the range of values of the cut angle φwhen the focal length H is 6 mm. FIG. 18C shows the range of values ofthe cut angle φ when the focal length H is 4 mm.

Even when the focal length H is reduced and the lens diameter R isincreased, values of the cut angle φ are in a range from 20° to 30°particularly shown in FIG. 18C, which are values at which the device canbe formed by the metal molds. That is, when the folded potion isprovided at the edge portion of the light shielding member, the lightshielding member having the large edge surface angle can be formed bythe metal molds to thereby suppress the generation of flare and ghost.

[Processing of Forming the Light Shielding Member by Metal Molds]

Next, the above-described processing of forming the light shieldingmember 502 by the metal molds will be explained with reference to FIG.19 to FIG. 24B. FIG. 19 is a flowchart explaining the processing offorming the light shielding member by the metal molds and FIGS. 20A and20B to FIGS. 24A and 24B are cross-sectional views of the lightshielding member 502 and so on processed in the processing of formingthe light shielding member.

First, in Step S111, an opening and a guide hole for positioning areformed in a plate material to be the light shielding member 502.

The light shielding member 502 shown in FIG. 20A is, for example, aplate-shaped member generated by mixing a powder carbon into a resinsuch as polyester. The plate-shaped light shielding member 502 is cut soas to open wide on one surface (the surface facing the image sensor) bymetal molds 551 and 552 to thereby form an opening 502 a as shown inFIG. 20B. At this time, a guide hole 502 b is formed at the same time.Here, a single-edged blade is used for cutting the opening 502 a toutilize suppleness in the metal die 552, thereby forming the opening 502a with the cut angle φ of approximately 30 degrees.

In Step S112, the opening 502 a is pressed so that the folded portion isformed in the opening 502 a of the light shielding member 502.

That is, as shown in FIG. 21, the opening 502 a is pressed by the metalmolds 561 and 562 to thereby form the folded portion in the opening 502a of the light shielding member 502. At this time, the light shieldingmember 502 is positioned with respect to the metal molds 561 and 562 bythe guide hole 502 b.

In Step S113, an adhesive tape for supporting the light shielding member502 on the image sensor is formed.

As shown in FIG. 22A, an adhesive tape 581 includes a protection tape581 a, an adhesive layer 581 b and a protection tape 581 c which arestacked.

First, as shown in FIG. 22B, an opening 581 d, a guide hole 581 e and acut 581 f are formed in the adhesive tape 581 by metal molds 591 and592.

Next, as shown in FIG. 23A, unnecessary portions of the adhesive layer581 b and the protection tape 581 c are peeled off by the cut 581 fformed in the adhesive tape 581.

Then, as shown in FIG. 23B, another protection tape 601 is attached tothe protection tape 581 c of the adhesive tape 581 from which theunnecessary portions are peeled off, thereby peeling off the protectiontape 581 c.

In the manner as described above, the adhesive tape 581 shown in FIG.23C is formed.

Return to the flowchart of FIG. 19, the light shielding member 502 andthe adhesive tape 581 are bonded to each other in Step S114. That is, asshown in FIG. 24A, the upper surface (surface facing the lens) of thelight shielding member 502 and the adhesive take 581 are bonded to eachother by the adhesive layer 581 b as shown in FIG. 24A.

Then, in Step S115, an unnecessary portion of the light shielding member502 is cut. That is, as shown in FIG. 24B, the unnecessary portionincluding the guide hole 502 b of the light shielding member 502 bondedto the adhesive tape 581 is cut by metal molds 611 and 612, therebyforming an outer shape of the light shielding member 502.

According to the above processing, it is possible to form the lightshielding member having the shape in which the folded portion is formedat the opening as well as the cut angle is made at the edge surface.

The light shielding member having the similar shape can be formed byetching metals or other methods, however, costs are extremely high. Onthe other hand, the light shielding member can be formed by cutting andpressing resin materials such as plastic by metal molds according to theabove processing, therefore, the light shielding member can bemanufactured inexpensively as well as on a massive scale, which canreduce costs for manufacturing the camera module.

The present disclosure is not limited to the above embodiment and can bevariously modified within a scope not departing from the gist of thepresent disclosure.

Furthermore, the present disclosure can apply the followingconfigurations.

(1) A solid-state imaging apparatus including

-   -   a solid-state imaging device photoelectrically converting light        taken by a lens, and    -   a light shielding member shielding part of light incident on the        solid-state imaging device from the lens,    -   in which an angle made between an edge surface of the light        shielding member and an optical axis direction of the lens is        larger than an incident angle of light to be incident on an edge        portion of the light shielding member.

(2) The solid-state imaging apparatus described in the above (1),

-   -   in which the angle made between the edge surface of the light        shielding member and the optical axis direction of the lens is        larger than the incident angle of light whose incident angle is        the largest of light incident on the edge portion of the light        shielding member.

(3) The solid-state imaging apparatus described in the above (1) or (2),

-   -   in which pads to which metal wires connected to a substrate are        connected are provided at an peripheral portion of a light        receiving surface of the solid-state imaging device, and    -   the pads are not arranged on an area closer to the light        receiving surface in areas defined by an intersection between a        surface of the solid-state imaging device and a virtual        extension surface of the edge surface of the light shielding        member.

(4) The solid-state imaging apparatus described in the above (1) or (2),

-   -   in which the light receiving surface of the solid-state imaging        device receives light incident from an opening of the substrate        having the opening, and    -   an edge surface of the opening does not intersect the virtual        extension surface of the edge surface of the light shielding        member.

(5) The solid-state imaging apparatus described in the above (3) or (4),further including

-   -   a sealing member sealing a gap on the light receiving surface of        the solid-state imaging device,    -   in which the light shielding member is provided on a surface of        the sealing member facing the lens or a surface thereof facing        the solid-state imaging device.

(6) The solid-state imaging apparatus described in the above (5),

-   -   in which a side surface of the sealing member does not intersect        the virtual extension surface of the edge surface of the light        shielding member.

(7) The solid-state imaging apparatus described in the above (2),

-   -   in which the shielding member is formed by printing a material        for printing on an optical filter arranged on an optical path        once or plural times.

The present disclosure contains subject matter related to thosedisclosed in Japanese Priority Patent Applications JP 2011-033690 and JP2011-105241 filed in the Japan Patent Office on Feb. 18, 2011 and May10, 2011, respectively, the entire contents of which are herebyincorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. An imaging apparatus, comprising: a lens havingan optical axis extending in a first direction; an optical filter havinga flat first surface that faces the lens, wherein the flat first surfaceis normal to the first direction; an image sensor having a lightreceiving surface arranged to receive first rays of light from the lensvia the optical filter; a substrate; at least one conductor arranged toelectrically connect to the image sensor; a resin surrounding acircumference of the at least one conductor; and a light shield arrangedbetween the lens and the image sensor to prevent second rays of lightfrom the lens from reaching the light receiving surface of the imagesensor while allowing the first rays of light to reach the lightreceiving surface of image sensor, wherein, in a cross-sectional view: afirst side surface of the light shield is located on a first side of theoptical axis and includes a first flat portion that forms an acute anglerelative to the first direction, the first flat portion faces the imagesensor, and a virtual extension of the first flat portion does notintersect the substrate.
 2. The imaging apparatus of claim 1, wherein:the image sensor is positioned with respect to the lens such that onesof the first rays of light that are incident on an end portion of thelight receiving surface have, relative to the first direction, a chiefray angle and a lower ray angle corresponding to the chief ray angle;and the first acute angle formed by the first flat portion relative tothe first direction is greater than the lower ray angle.
 3. The imagingapparatus of claim 1, wherein the optical filter comprises an infraredcut filter (IRCF).
 4. The imaging apparatus of claim 1, wherein thevirtual extension of the first flat portion of the light shield does notintersect the at least one conductor.
 5. The imaging apparatus of claim1, wherein the virtual extension of the first flat portion of the lightshield does not intersect the resin.
 6. The imaging apparatus of claim1, further comprising a cavity disposed between the image sensor and theoptical filter.
 7. The imaging apparatus of claim 6, wherein the cavityis sealed.
 8. The imaging apparatus of claim 1, wherein: the at leastone conductor comprises a plurality of conductors each arranged toelectrically interconnect the image sensor to the substrate; the resinsurrounds a circumference of each of the plurality of conductors; andeach of the plurality of conductors is attached at a periphery of theimage sensor.
 9. The imaging apparatus of claim 1, wherein the firstflat portion of the light shield is positioned such that a firsthalf-line that extends away from and that is perpendicular to the firstflat portion intersects a second half-line that extends away from andthat is normal to the light receiving surface of the image sensor. 10.The imaging apparatus of claim 9, wherein: the light receiving surfaceof the image sensor is disposed substantially in a first plane; and thefirst half-line intersects the first plane.
 11. The imaging apparatus ofclaim 10, wherein the first half-line intersects the light receivingsurface of the image sensor.
 12. An imaging apparatus, comprising: alens having an optical axis extending in a first direction; an opticalfilter having a flat first surface that faces the lens, wherein the flatfirst surface is normal to the first direction; an image sensor having alight receiving surface arranged to receive first rays of light from thelens via the optical filter; a substrate; at least one conductorarranged to electrically connect to the image sensor; a resinsurrounding a circumference of the at least one conductor; and a lightshield arranged between the lens and the image sensor to prevent secondrays of light from the lens from reaching the light receiving surface ofthe image sensor while allowing the first rays of light to reach thelight receiving surface of image sensor, wherein, in a cross-sectionalview: a first side surface of the light shield is located on a firstside of the optical axis and has a first point and a second point, thefirst point being positioned closer to the lens than the second point,the first side surface is positioned such that a first line through thefirst point and the second point forms a first acute angle relative tothe first direction, the first line is positioned such that a firsthalf-line that extends away from and is perpendicular to the first lineintersects a second half-line that extends away from and is normal tothe light receiving surface of the image sensor, and a virtual extensionof the first line does not intersect the substrate.
 13. The imagingapparatus of claim 12, wherein: the image sensor is positioned withrespect to the lens such that ones of the first rays of light that areincident on an end portion of the light receiving surface have, relativeto the first direction, a chief ray angle and a lower ray anglecorresponding to the chief ray angle; and the first acute angle formedby the first line relative to the first direction is greater than thelower ray angle.
 14. The imaging apparatus of claim 12, wherein theoptical filter comprises an infrared cut filter (IRCF).
 15. The imagingapparatus of claim 12, wherein the light shield includes a first flatportion that faces the image sensor, and a virtual extension of thefirst flat portion of the light shield does not intersect the at leastone conductor.
 16. The imaging apparatus of claim 12, wherein the lightshield includes a first flat portion that faces the image sensor, andwherein a virtual extension of the first flat portion of the lightshield does not intersect the resin.
 17. The imaging apparatus of claim12, further comprising a cavity disposed between the image sensor andthe optical filter.
 18. The imaging apparatus of claim 17, wherein thecavity is sealed.
 19. The imaging apparatus of claim 12, wherein: the atleast one conductor comprise a plurality of conductors each arranged toelectrically interconnect the image sensor to the substrate; the resinsurrounds a circumference of each of the plurality of conductors; andeach of the plurality of conductors is attached at a periphery of theimage sensor.
 20. The imaging apparatus of claim 12, wherein: the lightreceiving surface of the image sensor is disposed substantially in afirst plane; and the first half-line intersects the first plane.
 21. Theimaging apparatus of claim 20, wherein the first half-line intersectsthe light receiving surface of the image sensor.